Narrow Results

This paper introduces a novel sketch-based CSCW (Computer Supported Collaborative Works) system for UML design. Being different from traditional CSCW and CAD systems, our system uses free hand sketch as user interface, which will fully exploit the advantages of sketch — natural, convenient, and more capable of handling brainstorm. When using sketch as interface in CSCW systems, two problems have to be solved first: (1) how to store, edit and exchange sketch-based document consistently; (2) how to visualize sketch-based document. To solve the first problem, we propose a new document format SKETCH, which is able to represent sketches and related semantics. To solve the second problem, we propose an ontology-based conceptual model which is helpful of recognizing sketches and providing uniform visualization of sketches. To demonstrate our ideas, we have developed a prototype system that can support simple UML Class Diagram design in collaborative environment. It shows us good results, but still, more works are going to be done in the future.

Motivated by the need to support concurrent, collaborative access to shared documents, we have designed and validated an architecture that integrates existing and familiar systems for client editing software and document repositories. Through Web-services, we achieve an open system wherein numerous clients can use varied editing tools to fit their preferences and access documents distributed on a heterogeneous collection of document repository systems (configuration management systems, or CMS). Our simulation results on numerous client/server configurations validate our architecture and demonstrate an increase in concurrent access to shared documents; by adding a Lock Manager to the server, our system achieves a 67% reduction in check-out failures. Additionally, we present a novel algorithm that avoids operational transformation (OT) by utilizing a dynamic, hierarchical locking scheme that is transparent to the user. This algorithm maximizes concurrent access and enables edit caching to minimize communication costs.